Direct lighting luminaire



Sept. 26, 1950 w, ROLPH ET AL 2,523,394

DIRECT LIGHTING LUMINAIRE Filed July 25, 1944 2 Sheets-Sheet l I 24 /f M:7 l J. C]. v4:.- /0

INVENTOR. THOM/IJ W- ROLPH .KUPT FRANCK A TTORNEY Sept. 26, 1950 T. w.ROLPH ET AL 2,523,394

DIRECT LIGHTING YLUMINAIRE Filed July 25, 1944 2 Sheets-Sheet 2INVENTOR. THOMAS W. ROtPH q KURT FRANCK ATTORNEY Patented Sept. 26, 1950DIRECT LIGHTING LUMINAIBE Thomas W. Rolph and Kurt Franck, Newark, Ohio,assignors to Holophane Company, Inc., New York, N. Y., a corporation ofDelaware Application July 25, 1944, Serial No. 546,512

Claims. 1

The present invention relates to direct lighting luminaires, and is moreparticularly directed toward direct lighting luminaires employing highintensity tubular light sources such as high in tensity mercury lamps.

The 3000 watt 120,000 lumen mercury lamp, which is about 5 long andslightly more than an inch in diameter, is an extremely high intensitylight source and gives off a great amount of heat and owing to the heatdeveloped by the lamp it requires very open mounting to facilitatecooling. It is well adapted for high bay lighting.

The present invention contemplates luminaires more particularly designedto employ light sources of the type referred to wherein the fixture isdesigned for precise light control and re-direction and provided withadequate ventilation to maintain all parts at satisfactory operatingtemperatures.

According to the present invention the light control i effected byreflectors disposed to form a horizontal inverted trough whose sidewalls intercept light in a wide region above and below the horizontaland direct this light generally downward, part of it crossing the axisand part of it not crossing the axis, so that the light from one side ofthe reflector is mixed with light from the other side. The reflectorsforming the trough are separated or spaced apart above the lamp tofacilitate the passage of heated air. Supplemental reflectors interceptthe upwardly emitted light and reflect it into useful directions.

The accompanying drawings show, for purposes of illustrating the presentinvention, two embodiments in which the invention may take form, itbeing understood that the drawings are illustrative of the inventionrather than limiting the same.

In these drawings: 7

Figure l is a perspective view of a pendent luminaire;

Figure 2 is an end elevational view with parts in section;

Figure 3 is a fragmentary cross sectional view;

Figure 4 is a longitudinal sectional view; and

Figures 5 and 6 are views similar to Figures 2 and 4 showing a modifiedform of construction.

The fixture shown in Figures 1 to 4 employs two end members l0, [0usually in the form of casings. They have two downwardly and outwardlydivergent ribs or branches H, II. The end members are secured togetherby four sheet metal tie members I2, 12 at the top and I3, l3 at thebottom, suitable bolts I 4 being employed to hold the parts together,and have upwardly extending apertured lugs l5 by which the fixture maybe suspended. The lower tie members I3 are upwardly opening channels,while the upper The tie members on each side'of the fixture support archshaped glass plates ll, [1. These plates are preferably made ofprismatic glass pressed in the form of flat sheets, then heated and bentto the proper profile and subjected to heat treatment. The outer surfaceof these plates is smooth, while the inner surface is made up ofprismatic ribs l8 shown at a larger scale in Figure 3. The angle betweenthe faces of these ribs is indicated at being 90 and the ribs aresymmetrical. The reflector plates typically have such a contour that theincident faces of the mitered ribs are at right angles to light emittedfrom a source L. The light rays are not therefore deviated when theyenter the glass. They strike the outer surface at angles suitable fortotal reflection and pass out of the glass through the other surface ofthe same or a still different rib without deviation, so that the anglebetween the incident rays, such as l9, and the reflected rays, such as20 Figure 3, is a right angle.

In order to maintain a screening angle of 30 below the horizontal, orfrom the nadir, the luminaire is designed so that the lower edge of thereflector is approximately 60 from the nadir as indicated. Thehorizontal light rays, such as 2 I, striking the reflector with miteredribs will be diverted directly down as indicated at 22. Typical lightrays above the ray 2i are indicated by the ray 23, this being near bythe uppermost ray and approximately 30 above the horizontal. It isreflected out as indicated at 24, so as to pass just below the loweredge of the reflector. Upwardly directed light will therefore bedirected downwardly by the reflector and spread away from the nadir toregions approximately 30 from the nadir without crossing the axis. Atypical ray below the horizontal is indicated at 25, and this ray isreflected out as indicated at 20. The direct light below the horizontalwill therefore be reflected downwardly and across the luminaire axiswith the widest spread of the reflected light approximately 30 from thenadir so that this light reaches the same regions as the upwardlydirected direct light intercepted by the upper part of the reflector onthe other side of the luminaire. The fixture is therefore well adaptedto provide a light pattern wherein there is a very definite cut off atabout 30 below the horizontal'and there is a high building up of lightbelow the luminaire tie members 42 have outwardly extending flanges in aregion about 40 wide with a sharp falling off in intensity up to theregion about 60 from the nadir. The 90 miter ribs are preferred as theyare more efficient than ribs with other angles. With them the profile ofthe reflector is also better than with other angles. I

In as much as the reflected rays 22, 24, 26, have a constant deviationfrom the corresponding incident rays 2|, 23 and 25 (90 in the exampleshown) the profile of each side of the reflector coincides with a curvewhich makes the proper uniform angle (45 in the example shown) with theradiants. These radiants are coincident with the light rays intransverse planes. The extreme radiants make equal angles above andbelow the median radiant, which is horizontal. The length of the arc ofthe curve and its position. are so selected that'light reflected'fromthe top of the reflector escapes below the bottom edge of the reflectoron the same side while none of the light reflected from the lower partof the reflector is at angles farther from the nadir than the mostwidely, spread light reflected from. the top of the reflector.

The glass plates rest in place in the luminaire frame and are merelyheld against falling out by clips 30, and they are able to expand andcontract so as to withstand the extremely high "temperature to whichthey are subjected.

As shown in Figures 2 and 4 the fixture is provided with supplementalupper reflector 34 adapted to return the upwardly direct light notintercepted by the main reflector in a generally downward direction.This upper reflector is spaced substantially from the upper tie membersl2, 12 so as to provide ventilation passages as They are held togetherby tie members 42 and 43. The upper tie members support angles 44. Theangles 44 and lower tie members 43 support reflectors II, the same asthose previously described, and these are held against accidentalremoval by clips 45.

In Figures 5 and 6 the upper reflector 46 is a prismatic glass reflectorwith outer totally reflecting prisms 41 so that the upwardly directedrays 48 are returned toward the light source. The fixture of Figures 5and 6 has hanger eyes indicated at 49.

The two supply wires and 5! (Figure 4) for the fixture are brought intoa splicing chamber 52 in one end member and one wire fastened to theterminal of a, socket holder 53 while the other wir is spliced to a wire54 which comes out through hole 55. The wire 54 passes down along theend member through bushings 56 carried by the end members, up along theother end member and into the other splicing chamber where it connectsto the other lamp socket. In this manner the wiring is removed as muchas possible from the heat of the lamp.

Since it is obvious that the invention may be embodied in other formsand constructions within the scope of the claims, we wish it to beunderstood that the particular forms shown are but a few of these forms,and various modifications and changes being possible, we do nototherwise limit ourselves in any way with respect thereto.

What is claimed is:

1. A direct lighting luminaire comprising a horizontal tubular lamp, endmembers spaced beyond the ends of the lamp and having legs whichdownwardly and outwardly diverge from the region of the lamp axis, timembers connecting the ends of the legs and having upwardly openingchannels, other tie members above and close to the source but spaced forventilation, reflecting panels whose lower edges are received in thechannels of the lower tie members and whose upper edges are securedagainst the upper tie members, and a downwardly acting reflector aboveand between the upper tie membersand whose edges are spaced from theupper tie members to provide ventilation passages.

2. In a luminaire, a light source emitting divergent rays, a prismaticreflector intercepting divergentrays in a zone of substantially lessthan and transmitting them without change of divergence, the reflectorbeing generally concave to incident rays and having an externally smoothouter surface and an inner surface, the latter being composed of ribseach with an incident face substantially normal to the rays incidentthereon and a second light emitting face at substantially right anglesto the incident face, the bisectors of the rib faces being substantiallynormal to the outer surface, whereby light rays in the reflector strikesaid outer surface at angles for total reflection through the secondfaces of the ribs and for emission at substantially 90 to the originaldirection.

3. A luminaire as claimed in claim 2, wherein the angle of the zone oflight intercepted by the reflector is substantially 60.

4. A luminaire comprising a horizontal rectilinear light source and aninverted specular reflecting trough symmetrical bout a, vertical planethrough the source and having on each-side of said vertical plane aprofile generated by the movement parallel to the axis of the lightsource of a generatrix in the form of an arc of a curve which makesuniform angles with radiants emanating from the axis of the source, theportions of the reflector above the median radiant being disposed inspace to reflect direct light toward the nadir without crossing saidvertical plane and with an angular spread therefrom equal to the anglebetween the median radiant and the uppermost radiant, the portions ofthe reflector below the median radiant through the source being disposedin space to reflect light toward nadir and across said vertical planewith the same angular spread therefrom.

5. A luminaire as claimed in claim 4, wherein the median radiant is in ahorizontal plane.

6. A luminaire as claimed in claim 4, wherein the reflector isprismatic, externally smooth and provided with internal ribs withincident faces normal to direct light and emergent faces normal toreflected light.

7. A luminaire as claimed in claim 4, wherein the reflector isprismatic, externally smooth and provided with internal ribs withincident faces normal to direct light and emergent faces normal toreflected light, and the median radiant is in a horizontal plane.

8. In a luminaire, the combination with a horizontal rectilinear lightsource of an inverted specular reflecting trough extending substantially30 below the horizontal plane through the source and 30 above saidplane, and having in vertical planes a profile generated by the movementin a direction parallel to the light source of generatrices in the formof sectorsof curves which make an angle of substantially 45 with theradiants thereof, the radiants emanating from the axis of the lightsource.

9. In a luminaire, the combination with a horizontal rectilinear lightsource of an inverted prismatic reflecting trough extendingsubstantially 30 below the horizontal plane through the source and 30above said plane, and having in vertical planes a profile generated bythe movement in a direction parallel to the light source of generatricesin the form of sectors of curves which make an angle of substantially 45with the radiants thereof, the radiants emanating from the axis of thelight source, the reflector being externally smooth and having internalribs with incident faces normal to incident light and emergent facesnormal to the incident faces.

10. In a luminaire, the combination with a horizontal rectilinear lightsource of two transparent rectilinear reflectors each occupying a zonesubstantially 30 above and 30 below the horizontal plane through thesource, each having a smooth lower surface consisting of miter ribs andan externally convex, totally reflecting surface with a slope ofsubstantially 45 at the level of the light source, a decreasing slopeabove the said level and an increasing slope below said level wherebyupwardly emitted direct light in the zone above the horizontal isreflected downwardly and away from the vertical median plane through theluminaire and downwardly emitted direct light in the zone 30 below thehorizontal is reflected downwardly and toward the median plane.

THOMAS W. ROLPH.

KURT FRANCK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date A 2,015,235 Rolph Sept. 24, 19352,314,103 Raizner Mar. 16, 1943 2,337,437 Allen Dec. 21, 1943 FOREIGNPATENTS Number Country Date 627,376 France of 1927 652,708 France of1928 36,540 France of 1930 467,411 England of 1937 699,506 Germany of1940 832,638 France of 1938

